Thanks for all the replies to my first post .
Following on from that can I ask : If i decide to retain my 3.5T van and then get a trailer I know I will be over weight for none tacho use. But will I need to apply for an “o” licence ? After all, its only an add on and will onlybe used on a ad hoc basis.
I realise that the best solution would be to invest in a 7T truck but I cannot currently see it being fully and profitably used .
Thanks in advance
The way I understand it is if the trailers unladen weight is 1020 kgs or below then you don’t need an O licence. Not 100% sure though 
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As far as I am aware it it is over 3.5 t then it needs an ‘O’ licence
but I will stand corrected
You could always phone your local TC to clarify this
You could always ask the question in this forum
SAFETY, LAW AND WORKING TIME DIRECTIVE FORUM
I think you should be able to tow a trailer, albeit a small one. You can drive vehicles up to 3.5 Gross Vehicle Weight but if you add a trailer then the increased weight is known as the Train Weight, which is a different thing.
I might be talking out my arse though