What you need, if you are performing other people's music, is an MCPS license.
Go to www.mcps.co.uk and you can request the forms. Basically, you fill in all the details of the songs that will be on the album, in the order that they appear, who wrote them, etc. You also tell them how many copies you'll be making and how much they will be sold for, and they will tell you the fee.
Don't worry, it is not too expensive (might add an extra 50p per CD to your costs) but well worth it - if you don't have MCPS, you can get a massive fine!
