The ‘rent a room’ scheme means you can take in a lodger to live in a furnished room in your home, and it has a special exemption meaning you won’t have to pay tax on the first £4,250 you make each year. This is a huge tax break for most people and really ups the gain. Better still, as a landlord you’ll be expected to ask for a month in advance, which means ready cash comes in quickly.
If you don't want to do it full time, there's a good halfway house too, you can also just play guesthouse. Website Crashpadder allows you to list your spare room online, and take in travellers looking for a cheap place to stay. You can set the nightly cost, undercutting the local hotels, and you might just get to work on your language skills to boot.
How much? With a full-time lodger, you can take home £4, 250 without paying a penny of tax; if you've a desirable property and don't mind paying income tax on anything above this, you could easily add another £1,000.