One of the amazon.es daily deals is this Crucial MX300 525GB SSD for 107.90 euro, which works out at around 98 quid. Shipping extra, it was around a fiver last time I sent something to the UK.
For the money it's a decent enough SSD.
Cnet say "affordable, efficient and fast":https://www.cnet.com/products/crucial-mx300/review/
I've ordered one and thought I'd share. Remember, it's only this price today!