Had mine for 6 years + now, I can easily get over 30mpg without any problems at all ... with a push I could get close to the 40mpg.
So yes a V50 T5 will make a great dependable family car ... but if looked after properly, like most cars anyway. 120k is on the higher side but thats no problem at all really, you will most likely be coming round to a change of clutch and dmf ... although I did mine at 125k and there was still loads of life left!
I have owned mine from 45k and its now on 168k and I have to say its been absolutely brilliant. The only main problems I have had with the car are the ones I have given it which are modding problems. Apart from that the only problems the car has given me to date (not caused by my meddling) is the alternator failed, which then lead to a dead battery. Also condenser a/c issues with leak in condenser and then a failing compressor clutch which I sorted myself (But these issues are common on all the models and not specific to the T5's)
I would say that price you popped up is leaning more towards the higher side. Mine is an S40 so would probably be cheaper than the V50 but mine was £6.2k with 45k.
But its absolutely worth it, most power out of all the other P1 platform engines and its also easy to mod if you decide to go down that route
