The first thing to bear in mind is that the UK receives less sunlight/solar irradiance than the US or Australia so the standard advice cannot be copied over and applied here.
Australia average solar irradiance: 1825 kWh/year/m2 (climatebix)
US average solar irradiance: 1817 kWh/year/m2 (EPA.gov)
UK average solar irradiance: 949 kWh/year/m2 (Wikipedia)
We would recommend a 2:1 ratio between AC output of the solar inverter and DC capacity of the solar array. But make sure you adhere to the solar inverters maximum voltage per MPPT and maximum amps when stringing the array.
The standard approach when sizing the inverter is to typically not let the solar panel array capacity exceed 1.3x of the solar panel inverter AC output. The US and Australia recieve roughly the same solar irradiance, however the UK receives almost half as much.
On average, a solar panel inverter in the UK would be generating half as much electricity than an inverter in the US or Australia.
This is significant as solar panel inverters are least efficient when operating between 5-15% of their maximum. As you can see from the graph on the right, typically an inverter would be 70-85% efficient at 5-15%. Efficiency jumps to 94%+ when operating at 20%+.
The goal of your solar panel inverter should always be to maximise generation over the course of the year, not merely to have the highest peak generation in the summer (and then have poorer performance for 90% of the year).
Sticking to the maximum voltage per MPPT and maximum Amps - we'd recommed a 2x ratio. E.g a 10 kW array should have a 5 kW (hybrid) solar inverter.
Remember, a 5 kW hybrid solar inverter can also charge the batteries using DC electricity, therefore it can send 5 kW to the AC side plus 3.6kW+ to the batteries - giving a maximum solar generation of 8.6 kW.
You should not install a hybrid inverter with a lower AC output than the batteries as this would reduce the battery charge/discharge potential. Therefore a 3.6 kW - 5kW hybrid inverter would cover most residential installations in the UK.