Interesting you say this about Britpart, I ordered a service kit from fleabay, box arrived and all parts were Britpart. But I had no problems with either the quality or fitting, so I'm not sure what you base your adverse comments about them on? Pollen filter fitted fine, old on hadn't been done from new by the look of things, ditto the air filter / fuel filter. But all sorted now.
Back to the OP post, as has been said on here, if you aren't servicing it yourself, then find a recommended garage that can be trusted to do all the work that should be done. Between £100-£400, dependent on what needs doing, and then if anything extra is required, point your finger in the air and guess