Old B5.5 but new to me, need some guidence.

[TRW88]

I've just inhered a Y reg B5.5 TDi Saloon (130). It seems to be in fairly good condition apart from some cosmetic issues. There is a squeaky noise which im told is something to do with the fan belt tensioner, is this a major issue that needs addressing quickly? If so is it likely to be costly to fix?

The car has got ~220k on the clock and has recently had an oil and oil filter change. Is there any general advice help maintain reliability and perhaps performance, I'm a relative noob but have some knowledgeable friends that may be able to help me if you guys have any recommendations.

Cheers.