Grappling Martial Art to combine with ITF Taekwon-Do

I've been doing ITF TKD for 8 years now and I'm a 1st Degree Black Belt. I know people seem to think TKD has no punches but this is not true. ITF TKD does have punches but also knees, elbows, knife hands, eye gouging etc and yes in my class they are practised just as much as kicks. But I need a change as I think my grappling and ground game is awful compared to my stand up. I'm not looking to become a MMA fighter but I just want some completeness in terms of having 1 striking and 1 grappling/ground fighting art under my belt. I know that ground fighting doesn't compliment a 'typical WTF TKD' fighter at all because of the distance during sparring but I believe ITF has the close quarter fighting elements that a BJJ fighter might need for example. I'm 5'8 and average build. In terms of classes near me there is BJJ and Wrestling at the Gracie Barra gym here in Glasgow. They are very expensive however but still an option. I don't wish to stop TKD either. Judo is also an option here but the classes are quite far from where I live but possible with some effort. If anything I'm not looking for a sport orientated Martial Art. ITF isn't Sport orientated like WTF so I want something more traditional. There's also Wing Chun very close by and JKD which is something I'd love to do but Tommy Carruthers only answers with one word when you ask him something via email. Also if anyone lives in Glasgow and has been to Krause World can you tell me what it's like and if the JKD is good. Thanks