Screwfix delivery is free over £50, Toolstation is free over £10, not sure about sending it back if it failed.
Sorry, I don’t know about the bottom end of the market 20 to 30 quid, if you are going to use it again then maybe spend a little more.
As above, the blade is usually 82mm so take care with gouging the boards. You can clamp two or three boards together to get less overlap, or wasted passes.
Don’t do all your passes in one direction, unless the grain is lifting badly, swap the boards or yourself round often.
Keep an eye on the blade, if it gums up with resin, give it a shave with a good stanley blade with the power off.
Have a bit of scrap board with a small step of timber screwed to it so you can put the machine down without damaging the blade, they are quite brittle.