You should definitely without question be taking waterproofs haha. The rest of the UK is bad enough, but I can only imagine how bad and crazy the weather is up in Scotland and I live in Wales.
If you are going on a few days expedition then you need waterproofs. A midge net and gaiters are not crucial though, if you have them, and you can cope with the extra things then why not, if you don't I wouldn't worry too much about them.
You seem to know what you need to take though...... if you are struggling I have written a
kit list [nofollow] for an over night expedition, it wont be exactly what you need, but will hopefully give you an idea and just play around with it.
The expedition kit list - What to pack! | Like Hiking [nofollow].
[font=georgia, 'times new roman', 'bitstream charter', times, serif]PS.. lots of spare and dry socks wouldn't go too badly either