Poundlland version I think is much more aggressive, you can dilute it further or just be quick using it but Muck off is safer if you have an extra fancy bike. Also fenwicks concentrate is very good as good as muck off but you have to dilute it yourself but can work out much cheaper.
I've been on the lookout for that for a while, but none of the local ones have had it in. Not sure if it's just my local stores or if they've stopped doing it. Even when they did, stock around here was even more intermittent than Aldi/Lidl and that's saying something.
Poundland 'no more dirty bike' for £1 is great stuff. Works just like the bigger brands. Bigger bottle too.
1 liter for £4.99 from haldfords...