I would call them and ask which grade of shelter and bivvy has absolutely no holes or other heavier damages.
These tarps last a lifetime in civil use and are worth the investment unless your fire lighting skills aren't so great.
Beginners tend to burn holes into shelters and rather should start with a cheap one.
Rare genuine issue gen-1 old-skool woodland D.P.M general service shelter sheet - aka basha / tarp / poncho. Made from a much richer flavour of woodland D.P.M than later generations and highly recommended back in the day by team-E. Made from high quality sil-nylon fabric - a totally waterproof...
www.endicotts.co.uk
I assume that you own a rain suit or want to buy one anyway. In this case the British army tarp is surely the better option for you.
The German army poncho will last you for decades as well if you get one from around 1990, and not much older. The manufacturing date is printed inside at the chest.
It weighs like the British tarp, can be found for 20 to 25 € in usually very good confitions and has only 210 × 165 cm.
But that's also large enough as a tarp if you have a good bivvy bag, because mainly the bivvy bag keeps you dry.
British tarp and a rainsuit are heavier than just the German poncho of course. But that doesn't help you if you will always carry a rain suit anyway.
But if you can't afford bivvy, tarp and rainsuit now, take German army poncho and a good bivvy bag! That isn't optimal for England but it works pretty well. And you would get two high end quality items in very good conditions.
Tarp and Goretex suit you could get later, but surely never will regret to have bought the German poncho, because it's simply good.
That is no rain poncho like all the others.
It's a ABC protection poncho, designed to protect also against nuclear fall out, chemical and biological attacks and even for a short moment against fire.
Probably ridiculous in a third world war scenario, but it's indeed very robust!
And hey, I went for decades just with this poncho and nowadays mainly use an even slightly shorter, a bit lighter one although I have a 1000 € tent and a Goretex suit. I just don't want to carry that always around!
Poncho + bivvy is generally the lightest shelter option. What I mainly use is lighter than this, but just a bit.
I simply carry the a bit less robust option.
But if we talk about low budget on a professional level we talk about stuff that has a good chance to last a lifetime. It's no problem to afford such equipment and buying anything else would be totally idiotic in your position.
I have quite a lot of stuff. But recently bought indeed 3 German army ponchos.
Because they are good!