I bought the attenuator from eBay from for the bargain price of £25 these things are now cheap as chips from China and when I tested the unit with a VNA gave 20dB of attenuation at 50ohms from 1MHz to 600MHz which is as far as I bothered but the device will apparently work up to 3GHz but I couldn't vouch for that.
The combiner is a Merrimac 2 way 0 deg inductive unit from rf-microwave.com which cost just over £40 pounds which is cheaper than the mini-circuits equivalent unit and more than up to the job.
|Merrimac combiner with 20dB 30W attenuator|
With an extra 16dB of attenuation placed between the Anglian and the PA I measured just under 37dBm out which is good enough to drive my little Microset SR100 amplifier.
I couldn't measure the 2nd and 3rd harmonic product with my equipment but I did a quick check with my SDR and I couldn't see anything on the SDR# waterfall.