Short answer: The Yamaha Pacifica 112 is a great electric guitar for beginner to intermediate level. They’re £199-£225 online. The Yamaha F310 is a good beginner acoustic guitar and costs around £109
Long answer: I’ve always recommended the Yamaha Pacifica 112 as a fantastic beginners guitar. The J version costs around £169, the V version is £200. Get the V if you can afford it, but the J is still perfectly good enough to learn on.
I own a Pacifica and often take it to gigs as a back up guitar in case anything goes wrong with my main guitar. It’s good enough that I’d be comfortable playing live with it if necessary. They’re really versatile instruments and the build quality is consistently good. It will be a long while before you needed to ‘upgrade’ to a better instrument.
For acoustic guitar, many of my students have started out with the Yamaha F310. It does everything you need for a beginner guitar. It will get you started well. If you continue playing for more than 18 months and are really into it you might then consider upgrading to a higher quality instrument, but the F310 will keep you going for as long as you need.
There are lots of cheap electric guitars out there and the quality varies hugely. Personally, I would avoid anything less than £100, anything that comes in a ‘kit’ with an amp, and steer clear of Squiers. Also, don’t buy a guitar with a ‘floyd rose’ or ‘floating tremolo’. You don’t need to know what they are, just don’t get one! They make the guitar much more difficult to learn on.
The best thing you can do is go to a shop with someone who plays guitar and try it with them, but I realise that’s not always possible. If you do see anything online that you like the look of and want my opinion then email me the link and if I know anything about the make I’ll let you know.