Antenna choices

[BearcatZip]

Hi All - be getting a BC3600XLT with NXDN soon but also want to have the setup in my lounge to connect to a rooftop antenna with coax running outside and into the lower floor - any one advise which would be the best antenna for this with best range and do I need a specific type of coax or a booster or such ( been looking at a discone one about £60 for 25-1300mhtz
New to this so any info appreciated ? Cheers in advance