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Firstly how much cash can you make? Revenue and Customs allow you to earn £4,250 a year tax free from lodgers, that's just over £354 per month. Normally bills are included in the monthly rent so you could charge £80 per week to reach the threshold. That's more than handy money.

On another administrative note, you would also need to check with your insurance company and your mortgage provider. They are unlikely to object but they may need to add it as a note to your policy.

You will need to choose your lodger with care - you are letting a complete stranger into your home afterall. You should obtain references and credit checks and you can also use formal lodger agreements, similar to a tenancy agreement, for protection for both parties. You need to agree the amount of rent, how it is to be paid, the notice period for either party, what is included in the rent and what the lodger needs to pay for (i.e. any damage to property).

Once you have prepared the room and before you advertise the room, write a list of rules. You need to be prepared before you meet any prospective lodgers. When you do have a viewing, interview your lodger and give the chance for your lodger to ask questions. You both need to decide whether you would be able to share your house with this person and whether realistically you will be able to live under the same roof.

House rules that you may want to consider include smoking, alcohol use, visitors, overnight visitors, cleanliness of kitchen and bathroom, laundering, car-parking, noise levels, pets, etc. Lodgers generally share the use of your kitchen and your bathroom but do not use your living room.

Regarding the use of the kitchen and bathroom be sure to have set times when you both have use of them. For the kitchen have a designated place to store your food separately, both in cupboards and in the fridge, which neither of you raid! It's grim if you're looking forward to your meal, having planned it and bought the ingredients, to get to the point of cooking it and someone else has used your ingredients.

Once you have a lodger check that each of you are happy and check if any changes are necessary. Communication is key to a good lodger/landlord relationship.

Having a lodger isn't everybody's first choice but it can work well if you choose the right lodger. If you are willing to make some compromises and share your house, you could make some very handy Money in the air, tightening of credit in particular.