Stop paying credit card interest, 16-17 summer holiday camp, £10 Harry Potter and FREE posh soup. These are our Money Saving Expert Martin Lewis' Quick Deals for Friday July 22.

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.

Teen summer activity camp £50 (or free for some)

The English and Northern Irish National Citizen Service scheme gets 16-17-year-olds abseiling, canoeing and learning life skills during the summer holidays (including up to two weeks overnight stay and 30 hours' voluntary work in the community).

It's £50 or less, or even free for some as its subsidised by the Government. It doesn't matter if your kids are at school or not. If a teenager's been on a course before, they unfortunately can't go again.

To apply, enter your details on the National Citizen Service registration page and it will contact you to explain more. Register as soon as possible as once places are gone, they're gone. I've had great feedback on this about previous years such as "The change has been wonderful; it's something that a parent only hopes to witness, their child growing into a better person."

£10 Harry Potter and the Cursed Child book:

This 350-page script book which is releasing on 31 July is likely to be massively popular. So if you want it you can pre-order it now for £10 at a range of places reduced from its listed £20.

Top pick is Tesco Direct with free delivery and earn 100 Clubcard points (worth £1 in store and up to £4 on deals). There's also Amazon (free delivery), Smyths Toys (£2.99 delivery or free store pick up), Waterstones (£2.75 delivery or free store pick up) and WH Smith (£2.99 delivery or free store pick up).

Free £2ish New Covent Garden Soup:

Register on the New Covent Garden Soup Co website and print the £1 off coupon (you won't be able to show it on your smartphone).

Then at Morrison's the soup's half-price at £1 until this Sunday (24 July), so do it there and you can get it totally free. If there's no Morrison's near you Asda is £1.98, still not bad for a posh soup. There's no end date on the offer but the coupon is valid for 30 days from when you print it, and there's 30,000 vouchers available.

Paying interest on credit card debt - STOP! Totally free balance transfers

Anyone who listens to me, knows I talk a lot about balance transfer cards. They're a great way to cut the cost of your existing credit or store card debt, as it allows you to shift debt from old cards on to a new 0% card, often for a one-off fee, so all your repayments clear the actual debt rather than covering the interest. That means you'll be debt free quicker.

In the last eight weeks we've seen a raft of new best buys (see Martin's full best balance-transfers & eligibility calc guide for full help and how to find which is most likely to accept you).

Yet for many people the fees put them off. But now a price war on means three new cards, Tesco, The AA and Halifax (this is an 'up to' 0% so not everyone will get it) allow you to transfer debt to them for FREE for 24 months. So if you can clear the debts within that time there's no cost at all.

However if you need longer to repay, just pay the fee, you can get up to 41mths 0% with Virgin Money for a 4% fee, though MBNA is up to 40mths 0% with a lower 2.47% fee.

Remember to always follow the Balance Transfer Golden Rules: 1. Repay at least the monthly minimum or the bank can end the 0% deal. 2. Clear the card in full by the end of the deal or the rate rockets to 18.9%-20.9% rep APR. 3. Never withdraw cash or spend on the card as it's not at the 0% rate.