Honestly I think people talking about people in refugee camps with no access to local markets being desperate for stained clothing are being somewhat naive. The money being spent to ship clothes will almost always go a hell of a lot further in the local market than the value of the products that are used to send. Yes, people are incredibly grateful for clothes: but in many cases they would be more grateful for blankets, or sanitary towels, or medicine.
If there are no local markets available to them, which is very rarely the case but may be in some instances - for example the many Palestinian refugees trapped in Yarmouk camp in Syria - then they will be so cut off the clothes wouldn't get through either.
If money is donated to reputable charities who can source clothes and other goods locally, then there's a much higher likelihood everything provided will be useful. In your situation, I think selling the clothes in the UK and then sending the money would be much much more effective.There is no doubt in my mind the 7 thousand pounds could be used in a more effective way than providing the quantity of second hand clothes its likely to ship - not meant to belittle the efforts of those who donated, but being realistic about it.
For those who are saying they want to send clothes because they don't know where the money will end up - well, ultimately, you don't know where the clothes will end up, so you either make the decision to give, having done lots of checks, or you don't. There is a lot of monitoring of the charity sector these days, especially organisations funded by the DEC. Fears of corruption in my experience are overblown, certainly when it comes to money filtered through British aid agencies.