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@ vulcon - i thought the same as you, but that is what the instructions say, i need to wait till it's dry and then cut it, but i can't tell what tool they suggest using by the picture they've used. I think i am going to go for the knife and tool thing emeritus suggested. Thank you for all your help.
@margo, why don't you go on a website like rated people or check a trade, i've had some really good work done by people on there - just make sure they've got lots of good reviews as i have met a couple of idiots on there. Or failing that, give it a go yourself, if i can do it, anyone can