django 1.5 abstractuser / accessing information of logged on user

I am using CBV / django braces for authentication. My user authorisation model inherits abstractuser and adds a few fields which are foreign keys to two other models organisation and premises.

When a form initialises I want to be able to examine the details of the user logged in , look to see if they are a is_superuser  or is_staff and occupy my organisation and premises form fields accordingly using the values stored as foreign keys in the logged on and authenticated user. 

My main problem at the moment is that I get a KeyError for the line 'self.user=kwargs.pop('user')' centered on 'user'

#heating/forms.py

from django import forms

from .models import Organisation, Premises,  Heating_User, Room, Heater

class HeatingUserForm ( forms.ModelForm):

  def __init__(self, *args, **kwargs):

self.user=kwargs.pop('User')

super(HeatingUserForm, self).__init__(*args, **kwargs)

if self.user.is_superuser:

self.fields['premises'].queryset = Premises.objects.all()

elif self.user.is_staff:

self.fields['premises'].queryset = Premises.objects.filter(organisation=self.user.organisation)

else:

self.fields['premises'].queryset = Premises.objects.filter(id=self.user.premises)

 

#models.py

from django.conf import settings

from django.core.urlresolvers import reverse

from django.db import models

from django.contrib.auth.models import AbstractUser

class Heating_User (AbstractUser):

  jobtitle = models.CharField(max_length=255)

  organisation = models.ForeignKey(Organisation, null=True)

  premises = models.ForeignKey(Premises, null= True)

def __unicode__(self):

return self.username

def get_absolute_url(self):

return reverse('users-detail', kwargs={'pk':self.pk})