I have ordered from T & M in the past, everything has been OK, but now look out for the best value mail order. ie free postage, or more plant for your money offers. I have ordered from Jersey Plants from time to time. Last year one lot of plugs that I had ordered from them arrived in a terrible state. Who ever had packed them had omitted the inner packaging, and they all arrived in a jumble.(must have been a Friday) However after one phone call I was offered replacement or a gift voucher with no quibbles at all. Everything else I have ordered has been fine. Having said that I only order plug plants ie bedding begonias, violas and busy lizzie's, no large plants.
I try to buy locally, but sometimes you just can't get what you want and have to look on the Internet. I have had some wonderful plants from independent growers on eBay.