Hmm - well, you'd need 200 million of them, and they are 14.2cm * 7.5cm, so that is 2.13 million square metres.
Paper is typically in the range of 60-150 grams per square metre. I think the currency paper is on the lighter side of the papers I've seen, so call it 60 gsm (the BoE don't say what the paper density is). That means you'd need 127,800 kilos of paper
Hopefully I didn't slip any decimal points, there
US currency weighs 1 gram, and the size is roughly 0.01m^2, so they are on about 100gsm paper for their currency.
If we were on 100gsm paper, the pile would weigh 213,000 kg