Its kind of hard to explain in a couple of posts, especially without diagrams. Firstly...
Hi the laptop is a : HP G70-111EM
Well the good News
being you could use the HDMI connection for HDMI/DVI displays if you needed.
so assuming that a pub has 2 or more tv's i presume one of them would be like a master tv which the other tv's are connected to? so they all get the same picture?
I would think most of the time it would be a splitter unit to all displays rather than a master display to slave displays, but then there are countless configurations and equipment options so you may come across a master/slave configuration, or maybe even something else.
now basically what i need to know now i think is, what do i need to go from my laptop to that master tv? will the connection be the same in all the venues?
Because you are doing this as a mobile service to lots of different sites, as stated before, the configuration and equipment may be different to all. As you want to cover as many bases as possible, with the unit in my previous post and the connections on your laptop you can cover all the connections pictured in my previous post, also including scart, which I would say would account for nearly all equipment configurations you might come across.
The 2 not covered being BNC and Component. I wouldnt worry too much about those, BNC is an older style of connection almost exclusive to cctv
systems (which also may be covered by the above depending on configuration) and Component, which although more common than BNC, any equipment using this should also support one of the other connections too. So you would be pretty much covered.
also what if the master tv happened to be a bit away from were the dj sets up, i would need some kind of extended lead?
Yes you would need extension cables for each connection type, as to the maximum length you could go? Thats a hard one, simply because there is no definitive answer due to your requirements.
Its all down to the equipment and quality of the cables involved. As you will be connecting to different types of equipment its very hard to judge. A 20-30metre cable may work fine at one site, but refuse to work on a another. TBH although all the connection types will have a maximum recommended distance, I would think you should be ok at 10-15 metres before you start getting problems, but even then its not guaranteed. Further than that and you may need to also look at signal extenders/boosters over cat5 cable.
There are no all in one boxes to do the whole job, you can get ones that do hd, or composite, or a mix of a few but not all, even then they are not cheap. The trouble with more equipment means more setting up, more to go wrong and makes you less mobile.
Single connection boosters are around £30-40
A couple of the multiple connection boosters I found were around the £500-600 mark, and even then dont fully meet your requirements.
As for this,http://www.maplin.co.uk/pc-to-tv-box-223833
It does practically the same as the unit in my previous post, BUT it doesnt seem to have a VGA output (from the little info on the maplins site), so to connect to the other displays would mean you would lose your monitor.
Hope all this helps, in a boring, OMG type way, lol.
What sort of budget were you looking at for this project?
Apologies if its a bit jumbled I was sort of adding and re-adding bits while reading and typing.