I've been buying from Thompson and Morgan over 10 years. One thing is that I think they everything is completely overpriced. I always use Clubcard Boost with my Tesco Clubcard vouchers. Even when getting cashback with Quidco, using a promotional code etc etc when my plants arrive I always feel its poor value for money.
The main issue with me is the mini plugs. I have always had a lot of success with the plugs eg the fuschias which I potted on for 2 months which are now in the hanging baskets. I also have loads of beautiful Lilly Trees grew from bulbs from T&M. Roses from bareroots too. However, the mini plugs are a completely different story. Mine usually look healthy when they arrive but around 25% die some within a 1-2 days.
Thompson & Morgan entice you in with these mini plugs collections with photos of beautiful flowers. I bought the Perennial 'Best Value' collection and the Gardeners' World Cottage Garden Perennials offer which arrived a few days ago.
I emailed T&M 2 weeks ago about replacements for the Perennial 'Best Value' and have not heard anything. Some of the Cottage Garden Perennials have died or are wilting.
I will probably still buy from T&M in future but will not ever buy mini-plugs.