Fattony
you have already had some very good advice. A couple of things to think of is the regulation regime and pilots licenses.
EASA type aircraft are well documented but in future can only be flown by pilots that have an EASA pilots license.
Homebuilt types are Annex II aircraft and are administered by the LAA. These aircraft can be flown by pilots with an EASA license or a UK NPPL or PPL license but there are some restrictions on operations of those aircraft ie VFR no IMC, night or commercial operations etc.
There is another type of aircraft that is Annex II but operated on a CofA which allows pilots with an EASA license to fly them unrestricted in IMC at night etc. Pilots with a UK PPL can also fly them unrestricted, and pilots with a UK NPPL can fly them but within the restrictions of their license.
For a group owned aircraft you may want to consider such an aircraft.
For a two seat aerobatic/touring aircraft the Airtourer fits the bill nicely. There are a couple for sale in the UK now, look at the usual web sites for further details.
Always get an engineer to check a prospective aircraft over, the money will be well spent. They will scrutinise the log books and find things that the average pilot will know nothing about. They know the right questions to ask and what to look out for. Don't be put off by aircraft with high time engines or airframes. Engines can run 'on condition' for many many hours and years past TBO, but if you use the aircraft for hire or reward you will need to change the engine at TBO. Some aircraft do have higher maintenance costs than others especially if it has a lot of AD's (Airworthiness Directives) and SB (Service Bulletin) to be checked or complied with or 'lifed' components that need changing.
As a sole owner/operator for the last 16 years I can say that it is a rewarding if expensive hobby. Group ownership is a good way to go to get aircraft availability as reasonable cost.