Put slicks on the MTB. It's slow and heavy going because you're unfit!

get a good road bike and you will really notice the difference

chomps up the miles got mine from ebay before i came over here really looked after cost new around £1000 got it for £300

look around and you will always get a bargain , just have to put the legwork in

I think you're right. I've exhausted gumtree and craigslist so it's ebay next.

on your mountain bike you'll be sat upright - a racing bike is going to have different style geometry (more angled and reaching to drop handle bars) - its going to take time to get used to and depending on your flexibility/age gonna hurt a bit. Racing bike saddles are going to be slimmer generally than mt bike and your ass is not going to thank you for the first month.

if you are going to start doing 30k+ rides regularly and want to go out explore and need speed for that then yeah a road bike can be good and get into the group riding and soon be zooming along at 25-30kmh for hours at a time. Within road bikes there are different geometry setups - hardcore racing bike which bends you more and has you reaching down deeper for the drop bars, or a more relaxed style which is still racing style compared to mtb but more comfortable for endurance/long time on bike. i have had 3 road bikes and just switched from a racing aggressive style to a more relaxed style bike and the difference is huge in terms of how long i can ride the bike for. all road bikes are not the same - so when you look on ebay - look for the 'style' on the supplier website ( I have specialised roubaix - the specialised tarmac for example is aggressive race geometry).

There are lots of bargains on ebay. Familiarise yourself with the running gear (shimano sora, 105, ultegra, dura-ace - that is a lot of what defines the pricing as well as whether frame is carbon or not) . Go to a bike shop and look at the different gera change mechanisms on the different shimano ranges, the lower spec ones have different gear change mechanism to the higher spec ones

you may want to look at the straight handle bar bikes tourer/commuter/- not a heavy mt bike but light frame with similar gears to a road bike but they have relaxed geometry. so you sit up, thisis going to be more relaxed/comfortable to ride.

comfort is important - comfortable bike means you ride it more.

The single biggest thing on your mt bike (apart from the engine) will be the weight (cant fix that) adn then the tyres - you can buy slick tyres for mtb for about 20$ each so a 40$ investment will make you a lot faster on your current bike on tarmac. The other thing that slows down on mtb is the suspension - having suspension on the bike takes lots of the power from your pedal stroke away from translating into rotation on the wheel. if your suspension can be locked that will also help.

That is a great reply. Thank you, I now know where to look and what to look for.