Probably the biggest giveaway is that your car is a 2005 diesel, and AFAIK in 2005 most (if not all) diesel cars in the UK did not have an "active" DPF (although at that time the CAT on the diesel was said to reduce particulate emissions, see below about N22A converter).
The next giveaway is a bit more specific to the Honda diesel. The N22A (in the 7th gen) has the exhaust manifold on the back of the engine, whereas the N22B (in the 8th gen) has the exhaust manifold on the front of the engine. N22A does not have an "active" DPF system, N22B does have an "active" DPF.
But even if one ignores all the above, there are no control systems or sensors on the N22A for an "active" DPF.
If you look at the equivalent parts you can see what I mean.
Exhaust for N22A
http://www.lingshondaparts.com/honda_car_parts_selection?block_01=17SEA01&block_02=B__0202&block_03=3063&block_05=hcr
Exhaust for N22B
http://www.lingshondaparts.com/honda_car_parts_selection?block_01=17TL1A01&block_02=B__0202&block_03=3568&block_05=hcr
Both diagrams show a connection to diagram E-34-20 (which is labelled "converter")
"converter" for N22A
http://www.lingshondaparts.com/honda_car_parts_selection?block_01=17SEA01&block_02=E__3420&block_03=3063&block_05=hcr
Converter for N22B
http://www.lingshondaparts.com/honda_car_parts_selection?block_01=17TL1A01&block_02=E__3420&block_03=3568&block_05=hcr
The converter system on the N22A is 2-stage, a pre-converter and then the CAT itself. This is typical of early diesel CAT systems, which do reduce some of the particulate emissions. But it is not an "active" DPF system.
The converter on the N22B is an "active" DPF . By "active" I mean that it stops particulates to such an extent that there are sensors for the engine ECU to decide when to initiate a "burn" process to get rid of some of the particulates in the converter. It's pretty obvious that the N22B has many sensors and connections, which gives it away as an "active" DPF system.
In his defence, he may be confused between the two types of "converter" on a diesel. But the pre-converter and CAT system on the N22A is passive and never gets extra fuel to "burn" excess particulates from the system.
Anyway, the best way to check oil level, is on absolutely flat ground (not tilted in any direction) and with the engine cold. Reason for the latter is that most of the oil has then drained into the sump, and the dipstick basically measures the amount of oil in the sump. Also,
always wipe the dipstick and put it back in then pull it out to look. I do this a couple of times.
final edit:
Note that the thermal expansion of oil from 20C to 80C = 4%
(so I'm not convinced by the 'thermal expansion' explanation)