Let any FTO have a sniff at providing you classroom PPL theory and they'll take £25/hour very quickly.
The PPL theory isn't very challenging and can be studied in your own time at home. Make use of the multiple websites online for practicing mock exams. I used Pooleys books and found them excellent at the time.
Ensure you really learn the subject, they make the ATPLs a little easier when/if you go on to do them.
- If you've studied at degree level, the quantity in the PPL syllabus will seem very little!