Stars shape the chemical evolution of the Universe and provide essential insights into the building blocks of life. Space-based photometry missions such as CoRoT, Kepler, and TESS have propelled asteroseismology to unprecedented heights, allowing us to study stellar oscillations and access the internal layers of distant stars. Asteroseismology enables us to constrain transport processes and obtain precise and accurate stellar characterisations. This endeavour is of utmost importance given the current state of exoplanetary research, which demands advanced stellar characterisation to fully comprehend the intricate interactions between stars and planets. Looking forward, asteroseismic modelling will be pivotal in upcoming missions such as PLATO and CubeSpec. The PLATO mission, in particular, will leverage asteroseismology to measure stellar masses and evolutionary stages, facilitating precise characterisation of planet-hosting stars. This notably includes using stellar ages to date planetary systems. The objective of this project is to perform an advanced characterisation of multiple planet-host stars. The improved stellar parameters will then be used to revise the characterisation of the planetary parameters. Special emphasis will be placed on the quantification of systematic uncertainties and their influence on the stellar characterisation, notably the physical ingredients employed in stellar models, asteroseismic surface effects, and stellar activity. To address the first aspect, we will systematically vary model parameters (e.g., abundances, opacities) and assess their impact on stellar characterisation. This work is part of a long-term effort to construct a comprehensive map of the parameter space for this systematics. Ultimately, this map will serve as a reference for a modelling pipeline, allowing for interpolation within this parameter space to predict stellar characteristics under various conditions. By interpolating within this map, we will be able to efficiently estimate the effects of different physical ingredients on stellar models, thereby improving the accuracy of stellar characterisations. Asteroseismic surface effects will be assessed by comparing outputs from a PLATO-like modelling approach with an advanced procedure designed to mitigate these effects, the FICO procedure. Additionally, we will investigate the influence of magnetic activity on stellar characterisation by segmenting observational time series and performing asteroseismic analyses to track changes in fundamental stellar parameters such as mass, radius, and age. Recent findings have demonstrated a significant correlation between the age of the Sun, as determined through helioseismology, and the solar magnetic activity cycle (Bétrisey et al. 2024b). Specifically, age variations of up to 6.5% were observed between solar activity extrema. Given PLATO’s precision requirement of 10% in age for a distant Sun and the low levels of activity of the Sun, it is crucial to extend these studies to other asteroseismic targets.