Wow! Have you tried EBay? You may be able to do a search in the UK for a acid etch primer. There should be a manufacturer in the UK. I found someone who ships world wide but the cost is 52.00 for shipping. I know that's not an option. I guess because it flamible there are restrictions on shipping. I look around for you and see what I can find.
Edited to add
Here is a source if you use an airbrush,
http://www.frost.co.uk/eastwood-grey-self-etch-primer.html, I have used Eastwood products and always found them to be high quality
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Scott
Salisbury, NC
USS Iowa BB61 1943 post refit1:200 Trumpeter w/ Pontos detail up with deck
USS Missouri BB63 1945 1:350
In planning T2-SE-A2 tanker AO-82