WildManDan

This alongside turning down the intensity in the visualsettings worked, Thanks man I appreciate it

No we don't. We're fine with being on rockstars games 

I was able to launch game and use forceduty cmd with your plugins. With all plugins installed after forceduty cmd my game was totally freezing.
Delete:
 Unsafe Callouts (UnsafeCallouts.dll, UnsafeCallouts.ini, UnsafeCallouts.pdb at plugins\lspdfr and Unsafe Callouts AUDIO folder at lspdfr\audio\scanner  Section136Callouts (Section136Callouts folder, Section136Callouts.dll, Section136Callouts.pdb at plugins\lspdfr and Newtonsoft.Json.dll, XSerializer.dll from gta5 root folder)
  Without this 2 plugins other ones launched without problem for me

Looks like you have a wrongly configured mods folder. There are multiple "Cannot spawn vehicles or peds" messages.
You can disable mods by simply renaming the folder to anything else like "mods_". Try to load the game again and see if it works.

You could Edit the dispatch.meta and add the other police cars.
Or you could Edit the popcycle.dat and add VEH_COPCAR 02 at the end of every line except for the POP_SHEDULES beginning with "NET". That would make police1, police2 and police3 spawn naturally in the traffic. I hope you unterstand what I mean. 

Thank you for taking the time to leave all this advice its been useful in eventually finding a solution.
 
I've managed to narrow it down to a faulty xml file in the els folder, This els file has been replaced and now gta5 loads up A okay

Install these 3 (1, 2, 3) if you haven't already. You could also try deleting the vehicles.rpf and copying it again from your non-mods directory to make sure that your car files are 100% vanilla

You can try removing every modded thing in your directory (including every modded .asi file, scripts or anything similar) and maybe disabling the antivirus. Sometimes problems don't seem related to it but it's still the issue

Glad to hear you solved it and no problem for the help

Thanks, removing scriptHookVDotNet and stopping antivirus worked.

Do not "stop" your antivirus. If you already disabled it, reenable it.
antivirus's exclusions lists exist for a reason.

Weridly yes both are edited however this issue started occuring randomly as oppose to right after an edit, I have tried default gta visualsettings I have not tried reverting meta, Should I try using a vanilla vehicles.meta file?
 
And thank you, For your time, I appreciate it.
 

In the VCF, look for:
 
<!-- AUX CORONAS -->
    <ACORONAS>
        <Headlights DfltPattern="1" ColorL="white" ColorR="white" />
 
- Change 'Headlights DfltPattern="1"' to  'Headlights DfltPattern="0"'

This comment may be months late but this info was useful, Thank you.

No we don't. We're fine with being on rockstars games 

This comment may be months late but this info was useful, Thank you.

I cant seem to get fire trucks to respond to backup, neither lspdfr normal backup menu or the ultimate backup but they spawn in the world and through ragehook etc. I've also tried with computer+ still no fire backup
 
When I select for the fire backup nothing happens, every other backup unit spawns and arrives as usual. Could this be the model? 
 
I'm using the greater manchester fire and rescue service one.

I have no idea why I got a notification for this thread. How do you like..back out? 

The way I have been doing it is if you hit "m" and go to your police radio menu you can request a call from there. I'm fairly certain the "x" key no longer forces callouts.

Anyone know the key to force a new callout or force end one in 0.4? In 0.3, 'X' used to force and end callouts, though I'm not sure if that was default or I changed it.

Okay, I will do. I've uninstalled all the mods including LSPDFR, I'm reinstalling it all from scratch starting with lspdfr