Noticed my clutch slightly slip in high gear when I put my foot down , but when I pull away in first the biting point still feels half way up , does anyone think clutch is slowly going ?or something else ?

Could be starting to slip - can be more noticable in high gears.  I've got over 10k on a clutch that was only slipping a little on a Ford Ka, so I would hope you have a fair bit of life left in it depending on how you drive.

 

What sort of mileage is on your car?

It's done 70 k but was remapped back in 2007 so has been in standard clutch with more power for 7 years

Sounds about right then - my KA clutch used to slip more when it was warmed up and was intermittent for a while.  It would slip out of 4th / 5th going up long hills when I tried to power up, but was fine around town / motorways.  I changed my driving style to a lot more relaxed and it was fine for ages.  Got it changed when it started slipping all the time.