I suppose the million dollar question is why should other countries accept our terms? On what basis?
I suspect an independent UK's terms would be a lot less onerous and demanding than the EU's. 
All Britain will want to achieve from a trade deal is the ability to trade freely with that country, with minimal paperwork and low or zero tariffs.
I can't see Britain demanding contributions to our budget, the right of our people to live and work in that country and maybe even the regulatory burden would be less onerous. 
In theory it should be quick and simple. Just 2 countries thrashing out a deal, which the US and Australia managed in 2 years.
How long have they been negotiating TTIP? 
You do reaise with that statement about the uk not demanding the right to live in the others country will affect 1.2 million britons? The number who live abroad in the eu?
What does the leave campaign propose for these people? Should they be repatriated? Or just leave them hung out to dry?
It is simply another bit of "leave" campaign "magic maths" .... you close all the borders to immigrants, and demand everything the UK wants from the surrounding countries (who all capitulate because we are so wonderful) and the world is great.... we want it, we get it being the mantra.
The reality is those other countries actually make their own demands, and refuse to take on all the ex-pats living in their countries .. so .. we stop 500,000 immigrants (hooray .. look at the pressure that is no longer on housing/hospitals etc) .. but then 1,200,000 ex-pats come home ..... and all want somewhere to live, and many are elderly and need more medical services .....
but why let the truth get in the way of a good headline ??
That won't happen due to the Vienna convention. I do expect their to be bad feeling initially towards expats e.g. here in Spain. However they will get over it especially as I am now 100% convinced that even with an Out vote the establishment will ensure that it NEVER happens. I also predict a spectacular from Remain in the next 9 days. That will save years of political and legal wrangling to get an out vote overturned. Vested interests have far too much at stake to allow an out vote.The very best we can hope for is the Eu realises it needs to change direction and adapt to sentiment (something it has been spectacularly unsuccessful at). We in Spain are likely to get a Left wing coalition government on the 26th June. Bit of a change from the Conservative EU toe licker we have had. When the Eu fines Spain in Uly for failing to get its debt down enough I am expecting a backlash .
At no point did I say they would be SENT home ...

No treaty can stop folks DECIDING to return to UK. I have many friends, mostly ex-military, who have settled in Spain, Italy, Portugal, Cyprus, Greece etc ... and "survive" on savings/ pensions. With the extremely low interest rates their savings are no longer providing an income, and with the pound dropping against the euro (
http://www.xe.com/currencycharts/?from=GBP&to=EUR&view=1Y) down some 15% (ish) over the past year, and forecast to get worse, especially if Leave win. their UK (Sterling) pensions are being eroded as well. Add to that dramatic increases in medical insurance costs, rising cost of living in many places, and a lot of folks that I know are thinking seriously about returning to UK permanently. Some have gone as far as getting advice on selling their properties abroad before the shit fully hits the fan.
If enough ex-pats do the same it sort of erodes any benefit of blocking immigration, and thats before you decide you need MORE NHS staff to deal with the influx of elderly patients ..... and most NHS staff are immigrants ......