No offence but you need to research more before purchasing any rep. Its not a case of buy now ask questions later. However, this won't change anything for now so let's just try and sort it out.
Firstly, you shouldn't have been informed that they will do the same job. A 10% T8 will do nowhere near the same job as the recommended uv, the Arcadia T5 12% so I would definitely recommend upgrading this when you can. The sooner the better. This will help no end and should be the first on the list, its the only uv that can provide anything close to what they receive in the wild.
A red bulb isn't ideal but it will create the required hot spot but should definitely not be used at night regardless if its red or not. There should be no night time lighting regardless of the colour so use it only for day time heating. You shouldn't need ANY nightime heating unless the temp drops to 10c. 12 on, 12 off (heat/uv) is fine but seeing as its winter still you may want it a little less and increase it coming in to summer.
You can use a heatmat for night time heat if its needed, just don't set the stat to anything higher than 15c. As I said before though I would definitely not recommend a heat mat for the reasons I stated, most of the time its a useless risk.
100f in the warm end, that's too hot. Unless of course you mean basking spot in which case its too cool. Where are you measuring this temp and what with? Your hot side is taken as an ambient temp in the hot side, usually on the side wall. Your basking temp is taken in the hottest area of your viv directly under the spot bulb. Hot side should be 85-95f and basking 105-115f.
Unfortunately it would appear you may have slightly rushed in to it and bought kit that may well do the job but definitely not to its full potential. Personally I'd remove the heat mat. If you do need night time heat (check your night temps and see) then buy a ceramic heat emitter and pulse thermostat. I would purchase a standard household spot bulb from tesco, b&q etc and change it for your red basking bulb. REMEMBER NO LIGHTS ON AT NIGHT. While we're at it, how bigs the viv? And any pictures?