Help! My first mealies :(

[Skirril]

So yesterday I was trying to sort out a kink in a leaf in one of the young plants I bought a few weeks ago, and out came a mealy bug I looked at pics and that is definitely what it was, today I found one other in that kink. I got rid of both of them.

I got 5 plants from that grower, and as 3 were young plants and 2 were in flower I didn't repot any, but I did check them over carefully.

Do mealies tend to stay on one plant when there are only a couple of them? Or even though I only found 2 should I worry about all my plants now...? I have isolated the plant already. Should I spray all plants? (I check them regularly, they have no signs I know of).

Should I worry about all the plants I got from that grower or just this one?

Which is the best mealy bug killer available in the UK? (I was at an orchid show last week and nearly got some, but hubby was muttering about how much I had spent already, so I didn't >.<). I would prefer one available in shops or garden centres.

How thorough do I have to be (just bug killer or repot and bug killer or soak plant for 20 mins, repot and bug killer). I am confused about how tough it is to get rid of them, and perhaps when it's only a couple it doesn't have to be such a tough regime. At the show there was a talk where the guy said to soak for 20 mins, doesn't this risk rot??? And what about this being such a young plant? It's at least a year off flowering, maybe 2.

Thanks so much for any help, I was so gutted to see the damn thing, I bet if I had have got the killer at the show there wouldn't have been any bugs then :/