Hi I am Dan
Many thanks for your question
I would suggest trying www.247spares.com and www.findapart.com you will contact all of the spares agents in the uk here and get quotes to your mobile via text now if you get a good quote for a cylinder head I would be tempted to have it done, if you call around garages for quotes, you should be able to get the work done for £300. so as long as their is a part for the right price I think its well worth getting done.
if I can assist further please let me know