Not all DIY conservatory suppliers are the same, some will provide only the conservatory, others such as U-Fit Conservatories will provide a full fixing kit for your chosen conservatory together with support in overcoming any problems you may encounter.
The real key to success in finding a conservatory supplier is to find one that gives you the level of support you need in installing the conservatory. For instance if you are an independent builder and have been installing conservatories for years, the best option is to go for a product which gives the best value for money (quality and price). On the other hand if you an amateur DIYer building a conservatory for your own home, with no previous experience of conservatory installation the better the support package the supplier can offer you, the more likely you are to end up with a result that is up to your expectations.
A good directory of conservatory manufacturers, retail outlets and builders is Conservatory Frame where they have listings for all parts of the UK.