Is it correct to have the invertor so far away from the panels as I thought they normally go in the loft. Close to the panels
There's a general rule of thumb that it is better or safer to have a long 240v AC run in preference to a long 500v DC run. Hence the preference to mount inverters close to the panels.
There are differing views as to the suitability of lofts - they can get hot in summer causing inverters to overheat (not dangerous, but it will reduce their output). On the other hand the solar panels will act as a good heat shield reducing the maximum temperature of the loft.
The solar pv guides all state you should keep the voltage drop of the DC run to below 1% and the voltage drop of the AC run to below 1%. You can reduce the voltage drop by either reducing the length of the run or the thickness of the cable. Thick cable costs more, so a long run of thick cable can prove expensive.
In practice a drop of more than 1% in the DC cable is unlikely to cause any major problems as long as the voltage at the inverter is still within its operating range - the customer may not be impressed with the performance however, and it may not pass MCS/REAL inspections etc., and it is definitely not good or recommended practice.
A voltage drop of more than 1% in the AC cable can be more problematic. Grid voltages can typically be seen in excess of the nominal 240v and that could result in the voltage at the inverter going beyond the 253 maximum voltage after which it will perform a safety shut down. Again not dangerous per se, but not a good performance if the inverter shuts itself down for 10 minutes multiple times a day.
The potential danger with the install as described is that not only do the DC runs sound as if they look unsightly, but if they aren't secured properly they may rub against the
tiles which would wear the insulation. A spark cause by a worn DC cable could be a fire risk