Lets just stick to CE marking and not muddy the waters about any form of flight certification which has NOTHING to do with CE marking.

If your product meets ANY Directive, you are entitled to stick a CE mark on it and certify saying so. So pick one that you just can't fail on. Let's forget the fact that your product radiates spurious emissions further than Chernobyl, if it passes something like...

Machinery Directive 94/44/EEC
or The Low Voltage Directive 93/68/EEC
or The Low Voltage Equipment Regulations (Safety) 1989
or EN 50082-1
or EN 50082-2
or many others...

then you're entitled to write a little dinky self certification certificate and nail a CE mark on your product.

CE is regulated in the UK by Trading Standards... who have more work on their plate trying to protect the General Public from unhealthy eateries than they can cope with... like you're EVER going to get a Trading Standards Officer knocking on your door armed with anthing other than a spot thermometer and saying that for public helath reasons your product should be stored in the fridge at below 4C.

Just to look intelligent in case a TS Officer ever came calling, I've a copy of "EMC for Product Designers - Meeting the European Directive" ISBN 0750649305 sitting on my shelf. It's only for show... I've never bothered to look inside.