So I've baught "Arcadia D3 UV Basking Lamp, 100 W, E27" which emits UVA and UVB, so I need my 10.0 fluorescent UVB tube light anymore once it arrives or is it save to have it running anyway for when she's not basking?
Your Arcadia MVB should provide enough UVB and heat over the basking site when set at an appropriate distance (about 12-14''/30-35cm). If you have a large enclosure you could still use the T5 and set it to the front or back but you want to still have areas without UVB and provide a good gradient, just as you do with heat. Test it out and see how your dragon reacts with either setup and base your changes off of their reaction and behavior.