Thanks for all you replies everyone! I wasn't expecting so many responses so quickly!
@Beth_B Thanks for the welcome! I'm fairly sure it isn't the soil as I've tried several different soils and seem to have the same results every time. I'll definitely keep trying though!
@headfullofbees I'm also in Cheshire! Hello neighbour!
Thanks for that tip. I'll make sure it's sheltered from the wind!
@CanadianLori @IcyBC @claudine Thanks for the tip about partial sun! That could be a problem. How my house faces, either window I've been putting it in if I grow it inside is basically in full sunlight all day. I'll have to take a look at where else I can put it!
@Corzhens I love to eat basil! It's great with tomatoes which I also grow! When it grows well it seems to grow like crazy!
@gata montes I'd say the sunlight being too intense for too long might be the issue I've been having here. Where I lived before it probably only got sunlight for around 6 hours a day, and it was partially shaded because of how a tree cast a shadow as the sun moved. I'll definitely try your tips to get it to grow as a healthy bushy plant if I can get them to survive long enough!
Thanks for your help!