Go to specsavers, get a free eye test (vouchers online! - I can only speak for UK) and get the optician to do the colour test whilst there. They can write it out on a little slip, sign and stamp. That is sufficient.
Don't fork out for the Class 1 med just yet, Aer Lingus usually fund it if you get that far.
Regarding background checks, just do an online Basic Disclosure Scotland, £25. Reference/proof of application is sufficient.