Can anyone help !!

Epigrip will work well on an epoxy primed surface according to my techie guys, so they advise using Eposeal or a similar coating first. It's good stuff apparantly - have you got the hardener to go with it? We can produce a complete work schedule with cure times and application hints if that helps.
As for winter time in the UK - like I said, you do need to ensure the work area is protected from getting cold, but it is the dampness which will ruin the job - all epoxies love to soak up moisture while they are curing, which makes them weaker and heavier. I would advise against using chop strand matt glass fibre in the works - filler powders are much more effective at flattening surfaces and are easier to use.