Barnsleygal,
Just to put it in a different light - there is no harm in getting into good habits now. You will be expected to write correctly at all times during basic and NCAIT - in essays, defence writing etc. What the [old and] bold are doing is giving you a polite hint and perhaps trying to help you out in the long run. You are lucky they were kind enough to PM you about it, most would be hung, drawn and quartered in public!
Instead of getting all gobby about it, take it on the chin and get on with it. Learning this practise will also stand you in good stead for all the bull you will have to put up with during your training. Sometimes just letting it all ride over and taking heed the advice is the best thing you can do.
This may ONLY be Pprune but I can safely say, the more you do to make a good impression on here, the more willing people will be to help you. Same goes on
thestudentroom.co.uk; if you haven't already been over for a look. Couple of guys and girls currently applying for WSOp over there.