Here in my new home town of Devonport, Tasmania the local steel supplier will either sell cut pieces by the metre or will sell you whole 6m length and make as many cuts as you want for free, a signifficantly cheaper option. If the same applies in the UK it may be worth designing your frame and the choice of material sizes used around making best use of full lengths of one or two sizes only.

Looking forward to seeing how it goes.

kit