I presume you are talking about a (good quality) plumber style torch screwed on those yellow mapp bottles they sell at Screwfix etc?
You’ll never really be able to braze lugs with them – only silver solder. It takes a lot of heat to get a lugged bb hot enough for brass to flow through (factory frames are done in a brazing hearth with multiple burner heads).
You might manage to silver solder lugs, but it will be at the very limit of what they can manage. Silver flux gets “used up” quickly so works better if you are in and out quick with the heat (not trying to heat it up for ages with a weak torch). Not impossible, but I think you’ll find it difficult to make a strong and safe / fully flowed joint.
I braze with a small 6kg propane bottle and a medical oxygen concentrator. That was a bit expensive to set up but as home-safe as you can get and very economical on gas (6 frames so far on original bottle).
However I do use mapp for silver soldering little bits like cable guides, head badges etc as it is really quick and convenient. Cheap enough and handy to have regardless, so maybe get one and try some trial / scrap joints – cut them open to see if it has flowed through.
