Halve your mobile bill in minutes!

Hot sims, a passport warning, and January sales codes boost. These are our Money Saving Expert Martin Lewis’ Deals of the Week.

Remember, deals can change quickly, even while I’m on the programme. So always double-check the terms and conditions before spending. Plus, while I hope these deals will save you cash, don’t spend if you can’t afford it, don’t need it, or won’t use it.

Halve your mobile bill in minutes with the cheapest Sim only deals – many can save £100s The Sim only market has got seriously competitive, which means if you don’t need a new phone (or can buy one outright) most people can get a mobile at a fraction of the price (just ensure you’re out of contract). And if you’re out of contract, you should be able to call up your existing provider and ask them to unlock it for free.

And with all of these you can move your phone number across. For full help in cutting costs see Martin’s 30+ tips to slash your mobile bill guide, but in brief…

· Low users - pay £5/mthNew customers of iD mobile (through broadband choices website) which uses the Three network pay £5/mth for 2.25GB of data, 250 mins & 5,000 texts. It's a 30-day contract, so if you find you're using more you can switch again.

· Medium users - pay £9/mth. Anyone not currently in contract with Virgin Mobile (EE network) can get 5GB, unlimited texts & 1,500 mins (equiv to 50 mins' worth of calls per day) for £9/mth on a 12mth contract.

· High users - pay £14/mth.Three (through mobile phone checker website) can get 12GB + unltd mins & texts for £14/mth on a 12mth contract.

If you’re not sure what your usage is, try a free tool such as Billmonitor, which tells you your past use (but you need to give it your mobile account login) and matches you to Sims, though the ID mobile & Three sims aren’t available there (CHECK).

Booked your holiday? Check your passport & EHICs are valid January is the biggest booking month by far for holidays, so if you’ve booked yours already or are about to, check now if your passport is valid. Don’t leave it till just before you go – like Rach who tweeted me “@MartinSLewis watching/reading your tweets without too much thought for my own passport. Thankfully I had the light bulb moment to check my own!! Dubai in May would’ve been cancelled.”

Most passports are valid for ten years but some countries require you to have at least six months left on yours, if not you can be refused entry. So don’t delay – check both yours and your children’s now to see whether it’ll still be valid when you travel and the rules for that country.

Plus over 5.3m EHIC cards are out of date, check point 9 on yours to see. To renew go to the EHIC website (don’t google it could be a site tricking you into paying a charge – if you have to pay you’re in the wrong place) or call 0300 330 1350.

Martin’s Quickies:

The January sales are in full swing and many stores right now have extra discount codes as they push to get rid of last season and Christmas stock. Though as always it’s stock dependent.

- Extra 30% off Urban Outfitters: Go online to Urban Outfitters and enter the code SALEONSALE you can get an extra 30% off everything in the 'up to 75% off' sale (doesn’t work on full-priced items) – making it a max 82% off - until 11.59pm Sunday 4 February. You can also get the extra discount in stores if you quote the code at the checkout.

- Extra 25% off Nike: Go online to Nike and you can get an extra 25% off items in the 'up to 40% off' sale (not full-priced items) – making it a max 55% off - when you enter the code 25OFF at the checkout until 10.59pm this Sunday (28 January).

- Extra 20% off Oasis: Go online to Oasis and you can get an extra 20% off selected sale items that are already up to 60% off – so the max discount is 68% when you enter the code SALE20 at the checkout. There’s no end date, only till stocks last so if you want to use it go soon. The code's not valid in stores or on any full-price items.

- Extra 40% off the Body Shop: Go online to The Body Shop and you can get 40% off most full-price and sale items when you enter the code 14664 until 9am this Sunday 28 January. The offer's not available in stores and some items are excluded.

- £10 off £50 Amazon spend: Today only (Thursday 25 January) enter the code BIGTHANKS online at Amazon and you'll get £10 off when you spend £50 or more on selected items, until 11.59pm tonight. You can only use the code on items that are dispatched and sold by Amazon (this will be clearly marked on screen), if you buy items from Amazon Marketplace's third-party sellers, the code won't work. It can only be used once per Amazon account and you can't use it on baby products, video games, digital products, gift cards, and delivery charges.