Structural calculation on Pergola

I have issued a request for a pergola drawing to gain planning permission in the UK. In addition I would like a structural calculation to understand it the materials used are sufficient.

Attached is a drawing. In short I am using c24 rafters 150 mm x 50 mm x 4200 mm at 600 mm centres. These support 6mm toughened glass. Pergola is attached to a house (supporting wall_ and the other end 150 mm x 150 mm beams in c24 timber.

I would like a quote of is the material sufficient and will they hold snow weight for DH7 9FF. Sheltered (back garden).

If you can produce CAD drawings for Planning that would be good to although I have a separate project for that.

Ian