Buying a freehold from the church Commissioners can be legally "interesting"… I've spent a lot of time with our village Scouts and Guides over the years and we wanted to buy the freehold for a strip of land through which the only road access to our HQ ran. An unoffcial arrangement in 1946 between the vicar led to the 1st HQ being built on his chicken run (wartime meant he was unable to get more hens); no problems for the next 60 years.
Fast forward to the 2000's and with a new HQ built on land we managed to buy behind the original site, we started to try and buy the leasehold for the little access strip.
After more than 10 years we got offered a fair price, but the church set the terms and wanted to use their standard contract. Then it got really interesting, we got a document from their solicitors with dozens of pages of adenda. We were extremely fortunate to have a parent who was a really good land lawyer to strip away 98% of it.
We are not now responsible for the maintenance of a window in the diocesan cathedral or a small %age of the salary of the verger in in the local deanery church and others. It seems that when land was given to the local church in previous centuries, usually to build a school or church, then also there was some commitment to the church hierarchy for the allowing it to happen.
There will probably be some retentions on the land, they get a %age if you sell it at vast profit, you can't turn your house into a "house of ill repute" or a video store??? (always wondered about the video store bit)
Sorry about the length of this diatribe, just make sure your lawyer reads the small print, if it's a standard freehold transfer that should be fine; but look out for all the stuff at the end.
I would get the freehold if you can do it for a sensible price 